Identify Level Control Loop Tuning Problems
A level control loop is supposed to maintain a constant level of liquid at the bottom of the stripping tower where considerable amount of vibration exists, but it seems to have…
PLC Permissive for Motor Control
A engineer needs to write a PLC program to control a water pump driven by an electric motor. This water pump will be manually started and stopped by pushbutton switches,…
Process Control High Level Alarm Fault Analysis
An operator reports a high level alarm (LAH-12) displayed at the control room for the last 13 hours of operation, in this sour water stripping tower unit (where sulfide-laden water…
Compressor Emergency Shutdown Root Cause Analysis
The compressor emergency shutdown system (ESD) has tripped the natural gas compressor off-line three times in the past 24 hours. Each time the operator goes to reset the compressor interlock,…
Chemical Mixing Process using PLC
Design a PLC Ladder Logic for Chemical Mixing Process. We have RSLogix 500 PLC Programming software to create PLC logic and its simulation. PLC Chemical Mixing Process Problem Logic Step Conditions:…
Solenoid Valves Practical Problems
Suppose this valve control system has a problem. The control valve (LV-104) does not move to the full-open position as it should when the solenoid is de-energized, although it will…
PLC Automatic Pedal Switch for Speed Control
We need to use pedal switch control logic at machine work shop for speed control of motor. Write the PLC program for this application using ladder diagram. Pedal Switch for…
Different Types of Turbine Protective Devices
This article provides the list of different types of Turbine Protective Devices like turbine over speed trip, low lube oil pressure, axial displacement, turbine temperature and turbine vibrations. Turbine Protective Devices…
Troubleshoot Allen Bradley PLC Logic
A engineer needs to write a program for an Allen-Bradley CompactLogix PLC to control a pressure relieving solenoid valve in a gas processing system. A pair of high-pressure control switches…
Liquid Flow Control Loop Controller Action
A liquid flow control loop consisting of a flow transmitter (FT) to sense liquid flow rate through the pipe and output an electronic signal corresponding to the flow. A flow…
